I'm using a maxim ADC in my application from this family: http://datasheets.maxim-ic.com/en/ds/MAX1304-MAX1314.pdf
The devices have relatively low input impedance. If you look at Figure 5 in the above datasheet, on page 19, you can see the equivalent input circuit. My ADC is 0-5V range. My input signal however is in 0-10V range, so i have to reduce it to match the ADC.
If I use a resistive divider at the ADC input, it seems to me that I can not get a proper reading from the ADC due to the interaction between my 2 resistors, and R1 and R2 in figure 5. For example:
| Vdiv | Vin------Rdivider--------Rdivider---------> GND | | | | | | | R1 (3.33k) | | | | Csample | |-------/ ------| |------- | | | R2 (5K) | | | | | | | v | 0.9V
In the above figure, no matter what Rdivider values I chose, it seems to me that Vdiv will not be Vin/2.
Do I have to use an amplifier in the input for this case?